1 //===----------------------------------------------------------------------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8
9 #ifndef _LIBCPP___ALGORITHM_PARTITION_H
10 #define _LIBCPP___ALGORITHM_PARTITION_H
11
12 #include <__algorithm/iterator_operations.h>
13 #include <__config>
14 #include <__iterator/iterator_traits.h>
15 #include <__utility/move.h>
16 #include <__utility/pair.h>
17
18 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
19 # pragma GCC system_header
20 #endif
21
22 _LIBCPP_BEGIN_NAMESPACE_STD
23
24 template <class _Predicate, class _AlgPolicy, class _ForwardIterator, class _Sentinel>
25 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 pair<_ForwardIterator, _ForwardIterator>
__partition_impl(_ForwardIterator __first,_Sentinel __last,_Predicate __pred,forward_iterator_tag)26 __partition_impl(_ForwardIterator __first, _Sentinel __last, _Predicate __pred, forward_iterator_tag)
27 {
28 while (true)
29 {
30 if (__first == __last)
31 return std::make_pair(std::move(__first), std::move(__first));
32 if (!__pred(*__first))
33 break;
34 ++__first;
35 }
36
37 _ForwardIterator __p = __first;
38 while (++__p != __last)
39 {
40 if (__pred(*__p))
41 {
42 _IterOps<_AlgPolicy>::iter_swap(__first, __p);
43 ++__first;
44 }
45 }
46 return std::make_pair(std::move(__first), std::move(__p));
47 }
48
49 template <class _Predicate, class _AlgPolicy, class _BidirectionalIterator, class _Sentinel>
50 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 pair<_BidirectionalIterator, _BidirectionalIterator>
__partition_impl(_BidirectionalIterator __first,_Sentinel __sentinel,_Predicate __pred,bidirectional_iterator_tag)51 __partition_impl(_BidirectionalIterator __first, _Sentinel __sentinel, _Predicate __pred,
52 bidirectional_iterator_tag)
53 {
54 _BidirectionalIterator __original_last = _IterOps<_AlgPolicy>::next(__first, __sentinel);
55 _BidirectionalIterator __last = __original_last;
56
57 while (true)
58 {
59 while (true)
60 {
61 if (__first == __last)
62 return std::make_pair(std::move(__first), std::move(__original_last));
63 if (!__pred(*__first))
64 break;
65 ++__first;
66 }
67 do
68 {
69 if (__first == --__last)
70 return std::make_pair(std::move(__first), std::move(__original_last));
71 } while (!__pred(*__last));
72 _IterOps<_AlgPolicy>::iter_swap(__first, __last);
73 ++__first;
74 }
75 }
76
77 template <class _AlgPolicy, class _ForwardIterator, class _Sentinel, class _Predicate, class _IterCategory>
78 inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20
__partition(_ForwardIterator __first,_Sentinel __last,_Predicate && __pred,_IterCategory __iter_category)79 pair<_ForwardIterator, _ForwardIterator> __partition(
80 _ForwardIterator __first, _Sentinel __last, _Predicate&& __pred, _IterCategory __iter_category) {
81 return std::__partition_impl<__remove_cvref_t<_Predicate>&, _AlgPolicy>(
82 std::move(__first), std::move(__last), __pred, __iter_category);
83 }
84
85 template <class _ForwardIterator, class _Predicate>
86 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX20
87 _ForwardIterator
partition(_ForwardIterator __first,_ForwardIterator __last,_Predicate __pred)88 partition(_ForwardIterator __first, _ForwardIterator __last, _Predicate __pred)
89 {
90 using _IterCategory = typename iterator_traits<_ForwardIterator>::iterator_category;
91 auto __result = std::__partition<_ClassicAlgPolicy>(std::move(__first), std::move(__last), __pred, _IterCategory());
92 return __result.first;
93 }
94
95 _LIBCPP_END_NAMESPACE_STD
96
97 #endif // _LIBCPP___ALGORITHM_PARTITION_H
98